<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    /* 通配，相当于所有的父类 */
    /* * {
        color: red;
    } */
    
    .box {
        color: blue;
    }
</style>

<body>
    <div class="box">前端
        <div>html</div>
        <div>css</div>
    </div>
    <div>后端</div>
    <div>测试</div>
</body>

</html>